/*
* Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

using System;
using System.Collections.Generic;
using System.Text;
using ZXing.Common;
using ZXing.Common.ReedSolomon;
using ZXing.QrCode.Internal;

namespace ZXing.QrCode.Internal
{
   /// <author>  satorux@google.com (Satoru Takabayashi) - creator
   /// </author>
   /// <author>  dswitkin@google.com (Daniel Switkin) - ported from C++
   /// </author>
   /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source 
   /// </author>
   public sealed class Encoder
   {

      // The original table is defined in the table 5 of JISX0510:2004 (p.19).
      private static int[] ALPHANUMERIC_TABLE = {
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 0x00-0x0f
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 0x10-0x1f
      36, -1, -1, -1, 37, 38, -1, -1, -1, -1, 39, 40, -1, 41, 42, 43,  // 0x20-0x2f
      0,   1,  2,  3,  4,  5,  6,  7,  8,  9, 44, -1, -1, -1, -1, -1,  // 0x30-0x3f
      -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,  // 0x40-0x4f
      25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, -1,  // 0x50-0x5f
  };

      internal static String DEFAULT_BYTE_MODE_ENCODING = "ISO-8859-1";

      private Encoder()
      {
      }

      // The mask penalty calculation is complicated.  See Table 21 of JISX0510:2004 (p.45) for details.
      // Basically it applies four rules and summate all penalties.
      private static int calculateMaskPenalty(ByteMatrix matrix)
      {

         int penalty = 0;
         penalty += MaskUtil.applyMaskPenaltyRule1(matrix);
         penalty += MaskUtil.applyMaskPenaltyRule2(matrix);
         penalty += MaskUtil.applyMaskPenaltyRule3(matrix);
         penalty += MaskUtil.applyMaskPenaltyRule4(matrix);
         return penalty;
      }

      /**
       *  Encode "bytes" with the error correction level "ecLevel". The encoding mode will be chosen
       * internally by chooseMode(). On success, store the result in "qrCode".
       *
       * We recommend you to use QRCode.EC_LEVEL_L (the lowest level) for
       * "getECLevel" since our primary use is to show QR code on desktop screens. We don't need very
       * strong error correction for this purpose.
       *
       * Note that there is no way to encode bytes in MODE_KANJI. We might want to add EncodeWithMode()
       * with which clients can specify the encoding mode. For now, we don't need the functionality.
       */
      public static void encode(String content, ErrorCorrectionLevel ecLevel, QRCode qrCode)
      {
         encode(content, ecLevel, null, qrCode);
      }

      public static void encode(String content,
                                ErrorCorrectionLevel ecLevel,
                                IDictionary<EncodeHintType, object> hints,
                                QRCode qrCode)
      {
         String encoding = hints == null || !hints.ContainsKey(EncodeHintType.CHARACTER_SET) ? null : (String)hints[EncodeHintType.CHARACTER_SET];
         if (encoding == null)
         {
            encoding = DEFAULT_BYTE_MODE_ENCODING;
         }

         // Step 1: Choose the mode (encoding).
         Mode mode = chooseMode(content, encoding);

         // Step 2: Append "bytes" into "dataBits" in appropriate encoding.
         BitArray dataBits = new BitArray();
         appendBytes(content, mode, dataBits, encoding);
         // Step 3: Initialize QR code that can contain "dataBits".
         int numInputBits = dataBits.Size;
         initQRCode(numInputBits, ecLevel, mode, qrCode);

         // Step 4: Build another bit vector that contains header and data.
         BitArray headerAndDataBits = new BitArray();

         // Step 4.5: Append ECI message if applicable
         if (mode == Mode.BYTE && !DEFAULT_BYTE_MODE_ENCODING.Equals(encoding))
         {

            CharacterSetECI eci = CharacterSetECI.getCharacterSetECIByName(encoding);
            if (eci != null)
            {

               appendECI(eci, headerAndDataBits);
            }
         }

         appendModeInfo(mode, headerAndDataBits);

         int numLetters = mode == Mode.BYTE ? dataBits.SizeInBytes : content.Length;
         appendLengthInfo(numLetters, qrCode.Version, mode, headerAndDataBits);
         headerAndDataBits.appendBitArray(dataBits);

         // Step 5: Terminate the bits properly.
         terminateBits(qrCode.NumDataBytes, headerAndDataBits);

         // Step 6: Interleave data bits with error correction code.
         BitArray finalBits = new BitArray();
         interleaveWithECBytes(headerAndDataBits, qrCode.NumTotalBytes, qrCode.NumDataBytes,
             qrCode.NumRSBlocks, finalBits);

         // Step 7: Choose the mask pattern and set to "qrCode".
         ByteMatrix matrix = new ByteMatrix(qrCode.MatrixWidth, qrCode.MatrixWidth);
         qrCode.MaskPattern = chooseMaskPattern(finalBits, ecLevel, qrCode.Version, matrix);

         // Step 8.  Build the matrix and set it to "qrCode".
         MatrixUtil.buildMatrix(finalBits, ecLevel, qrCode.Version, qrCode.MaskPattern, matrix);
         qrCode.Matrix = matrix;
         // Step 9.  Make sure we have a valid QR Code.
         if (!qrCode.Valid)
         {
            throw new WriterException("Invalid QR code: " + qrCode.ToString());
         }
      }

      /**
       * @return the code point of the table used in alphanumeric mode or
       *  -1 if there is no corresponding code in the table.
       */

      internal static int getAlphanumericCode(int code)
      {
         if (code < ALPHANUMERIC_TABLE.Length)
         {
            return ALPHANUMERIC_TABLE[code];
         }
         return -1;
      }

      public static Mode chooseMode(String content)
      {
         return chooseMode(content, null);
      }

      /**
       * Choose the best mode by examining the content. Note that 'encoding' is used as a hint;
       * if it is Shift_JIS, and the input is only double-byte Kanji, then we return {@link Mode#KANJI}.
       */
      private static Mode chooseMode(String content, String encoding)
      {
         if ("Shift_JIS".Equals(encoding))
         {

            // Choose Kanji mode if all input are double-byte characters
            return isOnlyDoubleByteKanji(content) ? Mode.KANJI : Mode.BYTE;
         }
         bool hasNumeric = false;
         bool hasAlphanumeric = false;
         for (int i = 0; i < content.Length; ++i)
         {
            char c = content[i];
            if (c >= '0' && c <= '9')
            {
               hasNumeric = true;
            }
            else if (getAlphanumericCode(c) != -1)
            {
               hasAlphanumeric = true;
            }
            else
            {
               return Mode.BYTE;
            }
         }
         if (hasAlphanumeric)
         {

            return Mode.ALPHANUMERIC;
         }
         if (hasNumeric)
         {

            return Mode.NUMERIC;
         }
         return Mode.BYTE;
      }

      private static bool isOnlyDoubleByteKanji(String content)
      {
         byte[] bytes;
         try
         {
            bytes = Encoding.GetEncoding("Shift_JIS").GetBytes(content);
         }
         catch (Exception )
         {
            return false;
         }
         int length = bytes.Length;
         if (length % 2 != 0)
         {
            return false;
         }
         for (int i = 0; i < length; i += 2)
         {


            int byte1 = bytes[i] & 0xFF;
            if ((byte1 < 0x81 || byte1 > 0x9F) && (byte1 < 0xE0 || byte1 > 0xEB))
            {

               return false;
            }
         }
         return true;
      }

      private static int chooseMaskPattern(BitArray bits,
                                           ErrorCorrectionLevel ecLevel,
                                           int version,
                                           ByteMatrix matrix)
      {
         int minPenalty = Int32.MaxValue;  // Lower penalty is better.
         int bestMaskPattern = -1;
         // We try all mask patterns to choose the best one.
         for (int maskPattern = 0; maskPattern < QRCode.NUM_MASK_PATTERNS; maskPattern++)
         {

            MatrixUtil.buildMatrix(bits, ecLevel, version, maskPattern, matrix);
            int penalty = calculateMaskPenalty(matrix);
            if (penalty < minPenalty)
            {

               minPenalty = penalty;
               bestMaskPattern = maskPattern;
            }
         }
         return bestMaskPattern;
      }

      /**
       * Initialize "qrCode" according to "numInputBits", "ecLevel", and "mode". On success,
       * modify "qrCode".
       */
      private static void initQRCode(int numInputBits,
                                     ErrorCorrectionLevel ecLevel,
                                     Mode mode,
                                     QRCode qrCode)
      {
         qrCode.ECLevel = ecLevel;
         qrCode.Mode = mode;

         // In the following comments, we use numbers of Version 7-H.
         for (int versionNum = 1; versionNum <= 40; versionNum++)
         {

            var version = Internal.Version.getVersionForNumber(versionNum);
            // numBytes = 196
            int numBytes = version.TotalCodewords;
            // getNumECBytes = 130
            var ecBlocks = version.getECBlocksForLevel(ecLevel);
            int numEcBytes = ecBlocks.TotalECCodewords;
            // getNumRSBlocks = 5
            int numRSBlocks = ecBlocks.NumBlocks;
            // getNumDataBytes = 196 - 130 = 66
            int numDataBytes = numBytes - numEcBytes;
            // We want to choose the smallest version which can contain data of "numInputBytes" + some
            // extra bits for the header (mode info and length info). The header can be three bytes
            // (precisely 4 + 16 bits) at most.
            if (numDataBytes >= getTotalInputBytes(numInputBits, version, mode))
            {

               // Yay, we found the proper rs block info!
               qrCode.Version = versionNum;
               qrCode.NumTotalBytes = numBytes;
               qrCode.NumDataBytes = numDataBytes;
               qrCode.NumRSBlocks = numRSBlocks;
               // getNumECBytes = 196 - 66 = 130
               qrCode.NumECBytes = numEcBytes;
               // matrix width = 21 + 6 * 4 = 45
               qrCode.MatrixWidth = version.DimensionForVersion;
               return;
            }
         }
         throw new WriterException("Cannot find proper rs block info (input data too big?)");
      }

      private static int getTotalInputBytes(int numInputBits, Internal.Version version, Mode mode)
      {
         int modeInfoBits = 4;
         int charCountBits = mode.getCharacterCountBits(version);
         int headerBits = modeInfoBits + charCountBits;
         int totalBits = numInputBits + headerBits;

         return (totalBits + 7) / 8;
      }

      /**
       * Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).
       */

      internal static void terminateBits(int numDataBytes, BitArray bits)
      {
         int capacity = numDataBytes << 3;
         if (bits.Size > capacity)
         {
            throw new WriterException("data bits cannot fit in the QR Code" + bits.Size + " > " +
                capacity);
         }
         for (int i = 0; i < 4 && bits.Size < capacity; ++i)
         {
            bits.appendBit(false);
         }
         // Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for details.
         // If the last byte isn't 8-bit aligned, we'll add padding bits.
         int numBitsInLastByte = bits.Size & 0x07;
         if (numBitsInLastByte > 0)
         {
            for (int i = numBitsInLastByte; i < 8; i++)
            {
               bits.appendBit(false);
            }
         }
         // If we have more space, we'll fill the space with padding patterns defined in 8.4.9 (p.24).
         int numPaddingBytes = numDataBytes - bits.SizeInBytes;
         for (int i = 0; i < numPaddingBytes; ++i)
         {
            bits.appendBits((i & 0x01) == 0 ? 0xEC : 0x11, 8);
         }
         if (bits.Size != capacity)
         {
            throw new WriterException("Bits size does not equal capacity");
         }
      }

      /**
       * Get number of data bytes and number of error correction bytes for block id "blockID". Store
       * the result in "numDataBytesInBlock", and "numECBytesInBlock". See table 12 in 8.5.1 of
       * JISX0510:2004 (p.30)
       */

      internal static void getNumDataBytesAndNumECBytesForBlockID(int numTotalBytes,
                                                         int numDataBytes,
                                                         int numRSBlocks,
                                                         int blockID,
                                                         int[] numDataBytesInBlock,
                                                         int[] numECBytesInBlock)
      {
         if (blockID >= numRSBlocks)
         {
            throw new WriterException("Block ID too large");
         }
         // numRsBlocksInGroup2 = 196 % 5 = 1
         int numRsBlocksInGroup2 = numTotalBytes % numRSBlocks;
         // numRsBlocksInGroup1 = 5 - 1 = 4
         int numRsBlocksInGroup1 = numRSBlocks - numRsBlocksInGroup2;
         // numTotalBytesInGroup1 = 196 / 5 = 39
         int numTotalBytesInGroup1 = numTotalBytes / numRSBlocks;
         // numTotalBytesInGroup2 = 39 + 1 = 40
         int numTotalBytesInGroup2 = numTotalBytesInGroup1 + 1;
         // numDataBytesInGroup1 = 66 / 5 = 13
         int numDataBytesInGroup1 = numDataBytes / numRSBlocks;
         // numDataBytesInGroup2 = 13 + 1 = 14
         int numDataBytesInGroup2 = numDataBytesInGroup1 + 1;
         // numEcBytesInGroup1 = 39 - 13 = 26
         int numEcBytesInGroup1 = numTotalBytesInGroup1 - numDataBytesInGroup1;
         // numEcBytesInGroup2 = 40 - 14 = 26
         int numEcBytesInGroup2 = numTotalBytesInGroup2 - numDataBytesInGroup2;
         // Sanity checks.
         // 26 = 26
         if (numEcBytesInGroup1 != numEcBytesInGroup2)
         {

            throw new WriterException("EC bytes mismatch");
         }
         // 5 = 4 + 1.
         if (numRSBlocks != numRsBlocksInGroup1 + numRsBlocksInGroup2)
         {

            throw new WriterException("RS blocks mismatch");
         }
         // 196 = (13 + 26) * 4 + (14 + 26) * 1
         if (numTotalBytes !=
             ((numDataBytesInGroup1 + numEcBytesInGroup1) *
                 numRsBlocksInGroup1) +
                 ((numDataBytesInGroup2 + numEcBytesInGroup2) *
                     numRsBlocksInGroup2))
         {
            throw new WriterException("Total bytes mismatch");
         }

         if (blockID < numRsBlocksInGroup1)
         {

            numDataBytesInBlock[0] = numDataBytesInGroup1;
            numECBytesInBlock[0] = numEcBytesInGroup1;
         }
         else
         {


            numDataBytesInBlock[0] = numDataBytesInGroup2;
            numECBytesInBlock[0] = numEcBytesInGroup2;
         }
      }

      /**
       * Interleave "bits" with corresponding error correction bytes. On success, store the result in
       * "result". The interleave rule is complicated. See 8.6 of JISX0510:2004 (p.37) for details.
       */

      internal static void interleaveWithECBytes(BitArray bits,
                                        int numTotalBytes,
                                        int numDataBytes,
                                        int numRSBlocks,
                                        BitArray result)
      {

         // "bits" must have "getNumDataBytes" bytes of data.
         if (bits.SizeInBytes != numDataBytes)
         {

            throw new WriterException("Number of bits and data bytes does not match");
         }

         // Step 1.  Divide data bytes into blocks and generate error correction bytes for them. We'll
         // store the divided data bytes blocks and error correction bytes blocks into "blocks".
         int dataBytesOffset = 0;
         int maxNumDataBytes = 0;
         int maxNumEcBytes = 0;

         // Since, we know the number of reedsolmon blocks, we can initialize the vector with the number.
         var blocks = new List<BlockPair>(numRSBlocks);

         for (int i = 0; i < numRSBlocks; ++i)
         {

            int[] numDataBytesInBlock = new int[1];
            int[] numEcBytesInBlock = new int[1];
            getNumDataBytesAndNumECBytesForBlockID(
                numTotalBytes, numDataBytes, numRSBlocks, i,
                numDataBytesInBlock, numEcBytesInBlock);

            int size = numDataBytesInBlock[0];
            byte[] dataBytes = new byte[size];
            bits.toBytes(8 * dataBytesOffset, dataBytes, 0, size);
            byte[] ecBytes = generateECBytes(dataBytes, numEcBytesInBlock[0]);
            blocks.Add(new BlockPair(dataBytes, ecBytes));

            maxNumDataBytes = Math.Max(maxNumDataBytes, size);
            maxNumEcBytes = Math.Max(maxNumEcBytes, ecBytes.Length);
            dataBytesOffset += numDataBytesInBlock[0];
         }
         if (numDataBytes != dataBytesOffset)
         {

            throw new WriterException("Data bytes does not match offset");
         }

         // First, place data blocks.
         for (int i = 0; i < maxNumDataBytes; ++i)
         {
            foreach (BlockPair block in blocks)
            {
               byte[] dataBytes = block.DataBytes;
               if (i < dataBytes.Length)
               {
                  result.appendBits(dataBytes[i], 8);
               }
            }
         }
         // Then, place error correction blocks.
         for (int i = 0; i < maxNumEcBytes; ++i)
         {
            foreach (BlockPair block in blocks)
            {
               byte[] ecBytes = block.ErrorCorrectionBytes;
               if (i < ecBytes.Length)
               {
                  result.appendBits(ecBytes[i], 8);
               }
            }
         }
         if (numTotalBytes != result.SizeInBytes)
         {  // Should be same.
            throw new WriterException("Interleaving error: " + numTotalBytes + " and " +
                result.SizeInBytes + " differ.");
         }
      }

      internal static byte[] generateECBytes(byte[] dataBytes, int numEcBytesInBlock)
      {
         int numDataBytes = dataBytes.Length;
         int[] toEncode = new int[numDataBytes + numEcBytesInBlock];
         for (int i = 0; i < numDataBytes; i++)
         {
            toEncode[i] = dataBytes[i] & 0xFF;

         }
         new ReedSolomonEncoder(GenericGF.QR_CODE_FIELD_256).encode(toEncode, numEcBytesInBlock);

         byte[] ecBytes = new byte[numEcBytesInBlock];
         for (int i = 0; i < numEcBytesInBlock; i++)
         {
            ecBytes[i] = (byte)toEncode[numDataBytes + i];

         }
         return ecBytes;
      }

      /**
       * Append mode info. On success, store the result in "bits".
       */

      internal static void appendModeInfo(Mode mode, BitArray bits)
      {
         bits.appendBits(mode.Bits, 4);
      }


      /**
       * Append length info. On success, store the result in "bits".
       */

      internal static void appendLengthInfo(int numLetters, int version, Mode mode, BitArray bits)
      {
         int numBits = mode.getCharacterCountBits(Internal.Version.getVersionForNumber(version));
         if (numLetters > ((1 << numBits) - 1))
         {
            throw new WriterException(numLetters + "is bigger than" + ((1 << numBits) - 1));
         }
         bits.appendBits(numLetters, numBits);
      }

      /**
       * Append "bytes" in "mode" mode (encoding) into "bits". On success, store the result in "bits".
       */

      internal static void appendBytes(String content,
                              Mode mode,
                              BitArray bits,
                              String encoding)
      {
         if (mode.Equals(Mode.NUMERIC))
            appendNumericBytes(content, bits);
         else
            if (mode.Equals(Mode.ALPHANUMERIC))
               appendAlphanumericBytes(content, bits);
            else
               if (mode.Equals(Mode.BYTE))
                  append8BitBytes(content, bits, encoding);
               else
                  if (mode.Equals(Mode.KANJI))
                     appendKanjiBytes(content, bits);
                  else
                     throw new WriterException("Invalid mode: " + mode);
      }

      internal static void appendNumericBytes(String content, BitArray bits)
      {
         int length = content.Length;

         int i = 0;
         while (i < length)
         {
            int num1 = content[i] - '0';
            if (i + 2 < length)
            {
               // Encode three numeric letters in ten bits.
               int num2 = content[i + 1] - '0';
               int num3 = content[i + 2] - '0';
               bits.appendBits(num1 * 100 + num2 * 10 + num3, 10);
               i += 3;
            }
            else if (i + 1 < length)
            {
               // Encode two numeric letters in seven bits.
               int num2 = content[i + 1] - '0';
               bits.appendBits(num1 * 10 + num2, 7);
               i += 2;
            }
            else
            {
               // Encode one numeric letter in four bits.
               bits.appendBits(num1, 4);
               i++;
            }
         }
      }

      internal static void appendAlphanumericBytes(String content, BitArray bits)
      {
         int length = content.Length;

         int i = 0;
         while (i < length)
         {
            int code1 = getAlphanumericCode(content[i]);
            if (code1 == -1)
            {
               throw new WriterException();
            }
            if (i + 1 < length)
            {
               int code2 = getAlphanumericCode(content[i + 1]);
               if (code2 == -1)
               {
                  throw new WriterException();
               }
               // Encode two alphanumeric letters in 11 bits.
               bits.appendBits(code1 * 45 + code2, 11);
               i += 2;
            }
            else
            {
               // Encode one alphanumeric letter in six bits.
               bits.appendBits(code1, 6);
               i++;
            }
         }
      }

      internal static void append8BitBytes(String content, BitArray bits, String encoding)
      {
         byte[] bytes;
         try
         {
            bytes = Encoding.GetEncoding(encoding).GetBytes(content);
         }
         catch (Exception uee)
         {
            throw new WriterException(uee.ToString());
         }
         foreach (byte b in bytes)
         {
            bits.appendBits(b, 8);
         }
      }

      internal static void appendKanjiBytes(String content, BitArray bits)
      {
         byte[] bytes;
         try
         {
            bytes = Encoding.GetEncoding("Shift_JIS").GetBytes(content);
         }
         catch (Exception uee)
         {
            throw new WriterException(uee.ToString());
         }
         int length = bytes.Length;
         for (int i = 0; i < length; i += 2)
         {
            int byte1 = bytes[i] & 0xFF;
            int byte2 = bytes[i + 1] & 0xFF;
            int code = (byte1 << 8) | byte2;
            int subtracted = -1;
            if (code >= 0x8140 && code <= 0x9ffc)
            {

               subtracted = code - 0x8140;
            }
            else if (code >= 0xe040 && code <= 0xebbf)
            {
               subtracted = code - 0xc140;
            }
            if (subtracted == -1)
            {

               throw new WriterException("Invalid byte sequence");
            }
            int encoded = ((subtracted >> 8) * 0xc0) + (subtracted & 0xff);
            bits.appendBits(encoded, 13);
         }
      }

      private static void appendECI(CharacterSetECI eci, BitArray bits)
      {
         bits.appendBits(Mode.ECI.Bits, 4);

         // This is correct for values up to 127, which is all we need now.
         bits.appendBits(eci.Value, 8);
      }
   }
}